Ladybird Browser Shifts to Rust for Enhanced Safety
The Ladybird browser is undergoing a significant transformation by adopting Rust as its primary programming language, replacing C++. This decision comes after previous explorations of Swift failed due to its limited interoperability with C++ and restricted platform support beyond Apple’s ecosystem. Rust, with its mature systems programming ecosystem and widespread familiarity among Ladybird contributors, is deemed a better fit for the project’s needs.
Why Rust?
Initially, Ladybird dismissed Rust in 2024 due to its incompatibility with the object-oriented programming style prevalent in the web platform’s object model. However, the need for robust safety guarantees and a supportive ecosystem has driven the team to reconsider. With successful implementations in browsers like Firefox and Chromium, Rust’s ownership model now appears to align with Ladybird’s goals.
Porting LibJS
The project has started with LibJS, the JavaScript engine of Ladybird. This component, comprising the lexer, parser, AST, and bytecode generator, was chosen due to its self-contained nature and comprehensive test coverage. Using tools like Claude Code and Codex for translation, the team achieved byte-for-byte identical output with the original. The porting process, which would have taken months manually, was completed in just two weeks, resulting in approximately 25,000 lines of Rust.
Adopting Rust not only enhances safety but also aligns Ladybird with industry trends, potentially influencing other projects to follow suit.
As Ladybird transitions to Rust, the implications for the browser’s performance and security are significant. The move signals a growing shift in the programming landscape toward more memory-safe languages. Will other browsers accelerate similar transitions?
Sources: Hacker News